Conduit driving mechanism



Jan. 17, '1933. v. s. McKENNY 1,894,446

CONDUIT DRIVING MECHANISM Filed June 27. 1927 2 Sheets-Sheet 1 M21; 5.Mc/(emg o afa/ 6: M

ATTURNEY Jan. 17, 1933. v. s. M KENNY CONDUIT DRIVING MECHANISM Filed June 27, 1927 2 Sheets-Sheet 2 WVE/VTUR Mm (51 70K? Patented Jan. 17, 1933 STATES PATENT, ,oFFI-cE' v VAN S. MCKENNY, OF SEATTLE, WASHINGTON, ASSIGNOR TO NE PAGE MCKENNY COM- PANY, OF SEATTLE, WASHINGTON,

A CORPORATION OF WASHINGTON' connurr DRIVING MECHANISM Application filed. June 27,

My invention relates to improvements in mechanisms employed to drive conduit pipes and the like through the ground by means of compressed air, and to improvements in the method of assembling and operating the same. 7

In laying rigid conduit or pipe in the ground it is customary to dig a trench of sufli- Cient depth and width in which the conduit can be placed as the joints are made up by 10 means of couplings, the trench being filled in after the conduit is laid. A great deal of such conduit is used in the large cities to carry electricaliconductors for street lighting and other purposes, the conduit being buried inside the-curb line, beneath the side Walk.

7 Where concreteside Walks have been installed prior to laying the conduit, it is necessaryto remove the concrete along a row of squares in order to dig the trench. In such instances a considerable saving is effected by removing the concrete only where required to dig a number ofspaced and comparatively short trench sections, which are then connected by means of a series of tunnels'under .25 the undisturbed sections of the side walk.

Heretofore it has been customary to use a similar method of procedure in laying rigid conduit and pipes under the street in order to connect adjacent trench sections running par- '30 allel with the curb. This necessitates removing the paving and digging a number of short trench sections in the street and driving tunnels under the undisturbed sections in much the same manner as that employed for the side Walk runs.

Obviously this method is not only expensive, but also seriously interferes with the flow of traific in the street. Furthermore .faults in the replaced paving almost in- 0 variably occur over the trench sections.

I am aware that attempts have been made to force such ductsthrough the earth from one trench section to another by means of powerful mechanical ratchet jacks, but this method is applicable only where the ground 1927. Serial No. 201,764. v 7,

and for much greater distances than has heretofore been practicable. In manyinstances I have beenable to drive a continuousrun of conduit pipe through the ground under the street from the end of a trench at the property line on one side into a'hole or trench on the other side of a city street of ordinary Width without disturbing the paving or interferingv with the flow of traffic, and at a fraction of the cost necessitated by the use of the trench-and-tunnel method.v

The general. object of my invention is to provide :an improved method of, and improved means for, driving conduit pipe and the like. through undisturbed ground by' means of compressed air. 7

A specific object is to provide improved means for guiding and driving conduit pipe and the like through the ground under street paving and concrete sidewalks without dis- 7 turbing the same. I 1

An additional object is to provide im proved coupling means for joining the lengths of pipe as a necessary element of the mechanism used to drive conduit pipe and the like through undisturbed ground by means of compressed air. I

A further object is to provide improved means, as a driving head for conduit pipe and the like whereby the same may be driven through undisturbed ground by means of compressed air. V

Otherobjects, of the invention will be apparent from the following description, illustrated in the accompanying drawings and 55 covered by the appended claims. I

A preferred embodiment of my invention is illustrated in the drawings, throughout which like reference numerals are used to indicate like'parts- Figure 1 of the drawings is an exploded assembly of important parts of the compressed air operated driving mechanism, said parts being illustrated partly in: section and partly in elevation.

Fig. 2 is a drawing of the driving head of the mechanism partly in section and partly in elevation.

Fig. 3 illustrates the forward end of the driven pipe and the type of coupling which is 100 is a tight fit in a centering plug 19 of such and other parts'assembled for the driving of a conduit or pipe from a trench at one side, under-the paving, into a second trench at the other side of'a street.

Figure 6 is a sectional view through a portion of the street and trench and a side elevation of the assembled mechanism. 7

Referring particularly to Figs. 1 and 5 of the drawings, the driving mechanism consists preferably of a modified Ingersoll-Rand paving breaker 7 which is operated by compressed air supplied throughjan air hose 8 from a suitablesource of supply, not shown. The modifications embraced in my invention consist of machining the barrel-like projection of the front head Qsupplied with the standard paving breaker so as to reduce its length and diameter to suitable dimensions preparatory to shrinking on a substantial cup-like steel head piece 10, which'is'further secure'din position on front head 9 by welding circuniferentially at'll as indicated in Figs- 5 and 6. This is the only essential change required'for the drive element proper. Certain additional elements of the invention are necessary, however, for its successful operation. I

A steel retaining ring 12 is made a snug fit in end piece 10 and'a tool steel anvil disc 13 slightly smaller in diameter is inserted in the aperture of the retaining ring and bears against shoulder 10 of the head piece. A fibre cushion disc 14. of approximately the same diameter as the hammer disc is next inserted in the aperture, after which, with air hose 8 connected to the driver and to the source of compressed air, the driver is ready for the driving operation hereinafter described. i

The rearward end of the pipe 15 to be driven is equipped with a driving terminal 16, the threaded cupped end of which is screwed ontothe pipe, the smaller solid end being adapted to fit loosely within retaining ring 12 and bear against fibre cushion disc 14 as shown in Fig. 5. The unthreaded skirt of the cupped end is made a tight fit over the pipe in order to maintain the pipe and drivi ing terminal in true axial alignment and to prevent the buckling or breaking of the plpe at or near the end of the threaded portion.

The forward end of the pipe15 is provided with a suitable driving head which facilitates the opening of the ground as the pipe is driven through. The driving head 17, which I have found to be most satisfactory for this purpose may be constructed from a spirally fluted pipe reamer 18, the shank 18 of which dimensions as to be forced or driveninto a short section of extra heavy threaded pipe 20 which'forms the shank of the tool. The three pieces of the tool are securely fastened together by circumferential weldingat 21 and 21 as clearly illustrated in Fig. 2. The pipe reamer portion 18 of the driving head should .then be tempered to the proper degree of hardness, as the welding referred to has a tendency to draw the original temper. This driving head is secured to the end of the pipe by firmly screwing threaded shank 20 into coupling 22 which, in this case, isillustrated to fit both threaded shank 20 and the size of pipe to be driven.

The flutes 18' of driving head 17 are so spiraled that, as the head is driven into the ground, it rotates the pipe about its longitu dinal axis in the proper direction to keep the threaded connections screwed firmly 'together throughout the length of-the pipe, and said rotation also assists in preventing the earth from packing about the pipe. Thisis an important feature of theimprovement, as the several impulses'trans'mitted' longitudi nally'of the pipe during the driving opera tion have a tendency to loosen the threaded joints,'which then wear rapidly and'fail to transmit the impulses properly to the driving head, whose functionit isto open the way for the pipe. a

In'order to direct the pipe in a true course and to reduce the strain on the operator to a minimum I prefer to make use of a guide frame 23, thrust plates 28, and drive carriage 31, which are assembled in a previously prepared trench T as shown in Figs. 5 and 6. The trench is dug to a length of about '14 feet, approximately 2 feet6 inches wide and to such depth as will enable the conduit pipe to clear the other pipes and obstructions buried under the street. i

Guide frame 23 is preferably constructed of two lengths of iron pipe 24- joined in parallel fixed, space relation by means of several U shaped. steel straps 25 welded to their outer sides as shown at 25 in Fig. 6. Threaded steel end pieces 26 are welded to'the ends of pipes 24, each end piece 26 being adapted to receive a jack screw 27 having an enlarged cylindrical portion 27 provided with through holes 27 in transverse alignment and at right angles to each other. l he outer ends of'jack screws 27 havesemispherical ends.

Steel thrust plates 28 are each provided with an aperture 28 of sufficient diameter to pass the driving head and couplings used in connection. with the largest size pipe that can be driven bythe equipment, the center of the aperture being in horizontal alignment with ends of j ack screws 27.

means the operating center of? the pneumatic drivingmechanism; Semi-spherical dfepressions 528 and thrust plates 28 are secured in: the

assembled relation shown: by means of jack:

' screws 2?. These are screwed outward by:

means of the usual cylindrical bar notshown or proper size to enterholes 27", thus foreing the: thrust plates firmly against the endsof' the trench. The ends of jack screws 27 and depressions 28"" in the thrustpl'ates assure the proper positioning of the frame un1- der the most exacting operating conditions; The driver carriage- 3 1 is -preiierab lybuil t up: of; two hori'zon-tal lydisposed steel angle" pieces 32 so spaced as: to allow theirinner', downwardly projecting legs to slide freely alongthesurfaces of guide-frame pipes 24",- said pipes thus acting as horizontal guides. A heavy forward steel cross='angle 331 is se curelywelded v to guide angles 32 and isprovided with-a centrally disposedi U shaped notch in its upwardly projecting leg" adapted to: receive the neck 0t driving mechanism 7'. downwardly projecting? lug 34. having a: transverse hole near its lower" extremityis weld'ed to: the underside at the mid-point ofthe horizontally disposed legof cross'a'ngle The driver carriage is completed byweld'ing a rearward steel crossbar 35 to guide angles 32; A U sha'pedbend in crossbar 3'5 at' its center and the U-shaped notch in the" leg 0t cross-angle 33 serve to support and align the driver mechanism '1 axiallly with the line 01 travel along which it is desired todrive the pipe.

A flexible steel wire tension cable 36 provid'ed' at one-end with a; terminal thimbl'e is moved around pulleys 3 0 and l astened to lug 34E of the driver carriage: by means o1- sha-ckle 38; The other end of the cable is wound upon a suitable Windlass; notshown, thus propidinga very satisfactory means for forcing carriage and driver mechanism 7 forwardagainst driving terminal 1 6 during the driving process. I find that the tensioncable rigged in this way is one 017 the important elements contributing to the success oi the driving process. Itn'ot' only reduces the strain on theaoperat'or to a minimum, but

provides a firm yet slightly resilient means for transmitting the force of the recoil from the driver to the solidly anchored members ot the mechanism. The importance of this feature increases with the length of: pipe and with the resistance of the ground through which the pipe is driven Under ordinary conditionsit'is usually sufiicient'toireeve-cable 36 around only one pulley 3(1): of each thrust plate 528: as shown in; the drawings,- but. when a long; drive is attempted, orwhen: the ground is unusualilly hard, it is. desirable to rescue the cable around all: four oi tlie:pu;1leys;.thusre+- ducing considerably the force ofitli'e recoil transmitted toavthe winch: andz increasingi the efi ectiveness ofthe. blows: of: the pneumati cail'ly operated piston ofi the driver. element}.

In carrying out theqp'rocess, the trench: T

and hole are dugand the: apparatus asseinbled asshown: in! Figs? 5 and: 6, but with the pneumatic hammer 7 and carriage 31' slid? along guide frame to the rearward extremity of; travel. A length ofconduit, or other" pipe 15 equipped:- with driving terminal L6 and drivilng head 11, is placed in position by the operator with the driving head extending centrally through aperture 28" and bearing against the earth at the end of thetrench. The carriage and pneumatic hammer, with ring 1 2 anvil disc 13' and: fibre cushion disc 1-4 in place,- are their drawn for? ward by winding cable- 36 around the winch drum by the operatorsassistant until the endof driving terminal 1 6 bears against fibrecushion' dis'c 14 with considerable pres sure. Compressed airis then admitted to the pneumatic hammer from. air hose 8 by the operator, who opens the throttle valve of the device by grasping handle 39 and f-orcing throttle lever-4'0 back into the handle by pressure fronr the fingers orthehand; The piston of the pneumatic hammer; being re ciproca-ted in the barrel under the pressure of the air; delivers a; series of rapidly recurring blows to the anvil block 41' in. the-usual man ner[ The force of each blow" of the piston is transmitted by anvil. block 451: to; the end of driver terminal: 1 6 through the intermediacy or anvil disc 1 3 andi fibre cushion. disc 14, thus continuallywibrating and: driving" thepipe forward into the ground the inertia of the pneumatic hammer and carriage", and. the tension in cable 36 ma-intaining the effectivenessoftheblows in the desired: direction. Because of" the rapidity of the blows, the entire length: of pipe is ma'intained in: a. state of vibration which is transmitted to the surroundiing earth thereby continually agitating' the sameand preventing it: firom: packing against thewpipmthus greatly increasing the effectiveness of the blowsin driving; the pipe forward; whereupon anvil disc I3 is soon forced outward? from shoulder 10 and: anvil block 4 1 protrudes. more and more from the end of front head 9 asshown' in Fig; 1:, thus continuing the contact with discs 1'33 21/]?!(131'45 and continuing to transmit. the forceof: the blows delivered by? the reciprocating p ston. In the meantime the carriage and pneumatic hammer are being forcedsteadily forward by th eoperators assistant, who is stationed at: the winch; facing the operator control of the: pneumatic hammer;

Anvil: disc" 13 serves to distribute the; fierce of the blows; received from: anvil h'lock llqo'r the driver, uniformly over fibre cushion .disc

14:,1which in turn serves to transmit theforce.

= 13 and a new fibre disc 14 are inserted in the retaining ring, and the carriage and driver 7 are; again moved up into engagement with driving terminal 16, and the driving process regained, 1 1 en pipe- 15 has been driven into'the ground to nearly its, full length, the carriage and driver are withdrawn, driving terminal 16 is removed, and a coupling 42 is screwed securely onto the endv of the pipe. The threaded end of a second length of pipe 15 is then screwed into the other end of the couplin'g, preferably so the ends of the pipes meet atthe center, as shown in Fig.4 of the drawings. i a v The'unthreaded skirt portions 42 of the coupling are made atight fit over pipe secti0ns 15 and '15, which are maintained thereby in true axial alignment. Skirts 42 serve also as reinforcements to prevent thegbucklingor. breaking ofthe pipes at or near the ends of the threaded portions. Skirts 42 are beveled at 42" to facilitate the passageof the coupling through the ground.

, After pipe section 15-is securely connected to pipe section 15, driving terminal 16 is screwed onto the rearward end of the last mentioned section, the carriage and driver are drawn up intoengagement with the driving terminal, and the driving is continued as before. In thisway, section after section of pipe is added and driven forward until the driving head end is finally forced the required distance into hole H, where driving head'17 is removed. The last section of pipe is usually cut to the proper length, so that itis only necessary to unscrew the driving terminal 16 after removing the balance of the driving equipment in trench T to complete the job. The ends of the pipe projecting into trench T and hole H may then be treated in any way the nature of the job may dictate. i 1

Obviously a run of conduit or pipemay be .driven inthe opposite direction from trench Tby simply reversing the carriage and driver, and reeving cable 36 so as to draw them in the desired direction. In this way pipe runs may be driven from both ends of the trench, and, if desired, the two runs may i then be joined to make a continuous run;

. Manyruns of rigid conduit have vbeen: driven-underbusy streets by means oflthe equipment and method, of my inventionthrough all sorts of groundwithout having to disturb the paving in any way. In cases where rocks are encountered that are'so large. that theycan not be crowded to one side'by the driving head, the vibration of the driving a 1 head striking against the obstruction enables the operator or his assistant to accurately locate the obstruction, which may be readily removed through asmall-hole dug directly over the forward end of the pipe; After the obstruction is removed, the driving process is resumed as before. the obstruction is such that it cannot be re-. moved after the holementionedis dug, the carriage 31 and driver 7 are removed, after which the pipemay be withdrawn by means of the cable .36, the successive sections being removed by unscrewing at the couplings.- Guide frame 23 is then either raised, lowered ormoved sidewise' in order itofassure the pipes clearing theobstruction, after which it is again driven as previously described.

of standard construction and have referred to it as a driver it will be understood that this tool is one type of a pneumatic orcther high frequency percussion hammer and that other types of'pneumatic hammer may "be used, that will maintain the pipe continu the pneumatic hammer, it is obvious that the same results would be obtained by affixing' the cupped head 10, to the driving terminal 19 instead although experience has proven the arrangement illustrated to be more convenient. f

Having thus described my inventionwhat I claim as new and desire to secureby'Letters Patentis: .fl' 1 1. In a mechanism for-'driving-conduit pipe, a pneumatic driver comprisingastandard pneumatic hammer, a cupped fronthead for said hammer, retainingv ring fitting within and removable from the cupped portion of said head, an anvil disc within said ring engaged with the anvilblock of-said hammer, a conduit pipe, a driving terminal on the rearward end of said pipe, a cushion disc intermediate of said anvil disc and said Where the nature of While have described a preferred form of pneumatlc tool as beinga pavement breaker int driving terminal, and tensioned cable means for feeding said pneumatic driver forward" a standard pneumatic hammer, a cupped front head for said hammer, an anvil disc within said cupped head and engaging the anvil block of said hammer, a conduit pipe, a driving terminal on the rearward end of said pipe, a cushion disc intermediate of said anvil disc and said driving terminal, and tensioned cable means for feeding said pneumatic driver forward as said pipe is driven.

3. In mechanism for driving conduit pipe, a pneumatic percussion hammer providing a cupped front head, an anvil disc within said cupped head and engaging the anvilblock of said hammer, a standard conduit pipe, a driving terminal on the rearward end of said pipe, a cushion disc intermediate of said anvil disc and said driving terminal, and tensioned cable means for feeding said pneumatic hammer forward as said pipe is driven.

4. In a mechanism for driving conduit pipe, a pneumatic percussion hammer providing a cupped front head, an anvil disc within said cupped head engaging the anvil block of said hammer, a standard conduit pipe, a driving terminal on the reaward end of said pipe, a cushion disc intermediate of said anvil disc and said driving terminal, whereby said hammer may maintain said pipe in a state of vibration transmittable to the surrounding earth to agitate the same and drive said pipe forward coincident with said vibration, and tensioned cable means for feeding said pneumatic hammer formed as said pipe is driven.

The foregoing specification signed at Seattle, Wash, this 21st day of June 1927.

VAN S. MoKENNY. 

